328 research outputs found
The nonlinear anomalous lattice elasticity associated with the high-pressure phase transition in spodumene: A high precission static compression study
The high-pressure behavior of the lattice elasticity of spodumene, LiAlSi2O6,
was studied by static compression in a diamond-anvil cell up to 9.3 GPa.
Investigations by means of single-crystal XRD and Raman spectroscopy within the
hydrostatic limits of the pressure medium focus on the pressure ranges around
similar to 3.2 and similar to 7.7 GPa, which have been reported previously to
comprise two independent structural phase transitions. While our measurements
confirm the well-established first-order C2/c-P2(1)/c transformation at 3.19
GPa (with 1.2% volume discontinuity and a hysteresis between 0.02 and 0.06
GPa), both unit-cell dimensions and the spectral changes observed in
high-pressure Raman spectra give no evidence for structural changes related to
a second phase transition. Monoclinic lattice parameters and unit-cell volumes
at in total 59 different pressure points have been used to re-calculate the
lattice-related properties of spontaneous strain, volume strain, and the bulk
moduli as a function of pressure across the transition. A modified Landau free
energy expansion in terms of a one component order parameter has been developed
and tested against these experimentally determined data. The Landau solution
provides a much better reproduction of the observed anomalies than any
equation-of-state fit to data sets truncated below and above P (tr), thus
giving Landau parameters of K (0) = 138.3(2) GPa, K' = 7.46(5), lambda (V) =
33.6(2) GPa, a = 0.486(3), b = -29.4(6) GPa and c = 551(11) GPa
Infrared Absorption Investigations Confirm the Extraterrestrial Origin of Carbonado-Diamonds
The first complete infrared FTIR absorption spectra for carbonado-diamond
confirm the interstellar origin for the most enigmatic diamonds known as
carbonado. All previous attempts failed to measure the absorption of
carbonado-diamond in the most important IR-range of 1000-1300 cm-1 (10.00-7.69
micro-m.) because of silica inclusions. In our investigation, KBr pellets were
made from crushed silica-free carbonado-diamond and thin sections were also
prepared. The 100 to 1000 times brighter synchrotron infrared radiation permits
a greater spatial resolution. Inclusions and pore spaces were avoided and/or
sources of chemical contamination were removed. The FTIR spectra of
carbonado-diamond mostly depict the presence of single nitrogen impurities, and
hydrogen. The lack of identifiable nitrogen aggregates in the infrared spectra,
the presence of features related to hydrocarbon stretch bonds, and the
resemblance of the spectra to CVD and presolar diamonds indicate that
carbonado-diamonds formed in a hydrogen-rich interstellar environment. This is
consistent with carbonado-diamond being sintered and porous, with extremely
reduced metals, metal alloys, carbides and nitrides, light carbon isotopes,
surfaces with glassy melt-like patinas, deformation lamellae, and a complete
absence of primary, terrestrial mineral inclusions. The 2.6-3.8 billion year
old fragmented body was of asteroidal proportions
Smoking decreases the level of circulating CD34+ progenitor cells in young healthy women - a pilot study
Supporting Spartina: Interdisciplinary Perspective Shows Spartina As A Distinct Solid Genus
In 2014, a DNA-based phylogenetic study confirming the paraphyly of the grass subtribe Sporobolinae proposed the creation of a large monophyletic genus Sporobolus, including (among others) species previously included in the genera Spartina, Calamovilfa, and Sporobolus. Spartina species have contributed substantially (and continue contributing) to our knowledge in multiple disciplines, including ecology, evolutionary biology, molecular biology, biogeography, experimental ecology, biological invasions, environmental management, restoration ecology, history, economics, and sociology. There is no rationale so compelling to subsume the name Spartina as a subgenus that could rival the striking, global iconic history and use of the name Spartina for over 200 yr. We do not agree with the subjective arguments underlying the proposal to change Spartina to Sporobolus. We understand the importance of both the objective phylogenetic insights and of the subjective formalized nomenclature and hope that by opening this debate we will encourage positive feedback that will strengthen taxonomic decisions with an interdisciplinary perspective. We consider that the strongly distinct, monophyletic clade Spartina should simply and efficiently be treated as the genus Spartina
What do hospital decision-makers in Ontario, Canada, have to say about the fairness of priority setting in their institutions?
BACKGROUND: Priority setting, also known as rationing or resource allocation, occurs at all levels of every health care system. Daniels and Sabin have proposed a framework for priority setting in health care institutions called 'accountability for reasonableness', which links priority setting to theories of democratic deliberation. Fairness is a key goal of priority setting. According to 'accountability for reasonableness', health care institutions engaged in priority setting have a claim to fairness if they satisfy four conditions of relevance, publicity, appeals/revision, and enforcement. This is the first study which has surveyed the views of hospital decision makers throughout an entire health system about the fairness of priority setting in their institutions. The purpose of this study is to elicit hospital decision-makers' self-report of the fairness of priority setting in their hospitals using an explicit conceptual framework, 'accountability for reasonableness'. METHODS: 160 Ontario hospital Chief Executive Officers, or their designates, were asked to complete a survey questionnaire concerning priority setting in their publicly funded institutions. Eight-six Ontario hospitals completed this survey, for a response rate of 54%. Six close-ended rating scale questions (e.g. Overall, how fair is priority setting at your hospital?), and 3 open-ended questions (e.g. What do you see as the goal(s) of priority setting in your hospital?) were used. RESULTS: Overall, 60.7% of respondents indicated their hospitals' priority setting was fair. With respect to the 'accountability for reasonableness' conditions, respondents indicated their hospitals performed best for the relevance (75.0%) condition, followed by appeals/revision (56.6%), publicity (56.0%), and enforcement (39.5%). CONCLUSIONS: For the first time hospital Chief Executive Officers within an entire health system were surveyed about the fairness of priority setting practices in their institutions using the conceptual framework 'accountability for reasonableness'. Although many hospital CEOs felt that their priority setting was fair, ample room for improvement was noted, especially for the enforcement condition
The Effects Of N, P And Crude Oil On The Decomposition Of Spartina Alterniflora Belowground Biomass
We conducted a laboratory experiment to examine how the decomposition of particulate belowground organic matter from a salt marsh is enhanced, or not, by different mixtures of crude oil, nitrogen (N), or phosphorus (P) acting individually or synergistically. The experiment was conducted in 3.8 L sampling chambers producing varying quantities of gas whose volume was used as a surrogate measure of organic decomposition under anaerobic conditions. Gas production after 28 days, from highest to lowest, was +NP = +N \u3e\u3e\u3e +P, or +oil. The gas production under either +P or +oil conditions was indistinguishable from gas production in the control chamber. Nitrogen, not phosphorus, or +NP, was the dominant factor controlling organic decomposition rates in these experiments. The implication for organic salt marsh soils is that shoreline erosion is enhanced by salt marsh oiling, presumably by its toxicity, but not by its effect on the decomposition rates of plant biomass belowground. Nutrient additions, on the other hand, may compromise the soil strength, creating a stronger disparity in soil strength between upper and lower soil layers leading to marsh loss. Nutrient amendments intended to decrease oil concentration in the marsh may not have the desired effect, and are likely to decrease soil strength, thereby enhancing marsh-to-water conversions in organic salt marsh soils
Pharmacological Aspects of Vipera xantina palestinae Venom
In Israel, Vipera xantina palestinae (V.x.p.) is the most common venomous snake, accounting for several hundred cases of envenomation in humans and domestic animals every year, with a mortality rate of 0.5 to 2%. In this review we will briefly address the research developments relevant to our present understanding of the structure and function of V.x.p. venom with emphasis on venom disintegrins. Venom proteomics indicated the presence of four families of pharmacologically active compounds: (i) neurotoxins; (ii) hemorrhagins; (iii) angioneurin growth factors; and (iv) different types of integrin inhibitors. Viperistatin, a α1β1selective KTS disintegrin and VP12, a α2β1 selective C-type lectin were discovered. These snake venom proteins represent promising tools for research and development of novel collagen receptor selective drugs. These discoveries are also relevant for future improvement of antivenom therapy towards V.x.p. envenomation
Supporting Spartina: Interdisciplinary perspective shows Spartina as a distinct solid genus
In 2014 a DNA-based phylogenetic study confirming the paraphyly of the grass subtribe Sporobolinae proposed the creation of a large monophyletic genus Sporobolus, including (among others) species previously included in the genera Spartina, Calamovilfa, and Sporobolus. Spartina species have contributed substantially (and continue contributing) to our knowledge in multiple disciplines, including ecology, evolutionary biology, molecular biology, biogeography, experimental ecology, environmental management, restoration ecology, history, economics, and sociology. There is no rationale so compelling to subsume the name Spartina as a subgenus that could rival the striking, global iconic history and use of the name Spartina for over 200 years. We do not agree with the arguments underlying the proposal to change Spartina to Sporobolus. We understand the importance of taxonomy and of formalized nomenclature and hope that by opening this debate we will encourage positive feedback that will strengthen taxonomic decisions with an interdisciplinary perspective. We consider the strongly distinct, monophyletic clade Spartina should simply and efficiently be treated as the genus Spartina
Oil pollution in the North Sea: the impact of governance measures on oil pollution over several decades
Oil pollution entering the marine environment has been an issue of concern for many decades. It can come from riverine or land-based sources, accidental and intentional discharges from ships, or as a
by-product of offshore oil extraction. Growing awareness of the impact of oil pollution on the marine environment has led, since the late 1960s, to the introduction of measures to reduce or eliminate pollution from shipping and the offshore oil industry. A framework for environmental protection of the North Sea has developed over many decades through
international agreements, regional cooperation, and national measures, while education has also played an important role with modern-day sailors being given due training to understand that dumping waste at sea is illegal in many areas, and is harmful to the marine environment. This paper presents data on trends in pollution from ships and oil installations. While significant reductions in oil pollution have been identified over more than two decades, there remain some areas where action is needed to reduce inputs still further, especially from oil and gas platforms
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